Intravascular balloon catheters are used in a wide variety of medical procedures to diagnose and treat vascular abnormalities such as aneurysms, stenotic lesions, intracranial shunts, etc. Such balloon catheters may be used for purposes of dilation, occlusion, flow control, tissue reformation, or the like. Balloons, in particular generally elastic balloons, have also been included on guide catheters to arrest blood flow near a treatment site while another treatment device is extended into a treatment area beyond or distal of the balloon and guide catheter.
Intravascular balloon catheters are commonly navigated through the vasculature to access remote regions of the human body. In order to navigate a vasculature during an intended medical procedure, a catheter must possess opposing characteristics of trackability and flexibility, while retaining a relatively low profile. It is also beneficial that catheters possess a soft distal tip to lessen injury to a vessel wall during navigation through the vasculature.
The hardness or durometer of polymer materials such as those typically used in catheters is commonly measured using the Shore Hardness Test. The Shore Hardness of such materials may be measured by using either the Shore A or Shore D scale. The Shore A scale is used for softer materials, while the Shore D scale is used for harder materials. Both scales range from 0 to 100, where the upper end of the Shore A scale overlaps the lower end of the Shore D scale. For example, a Shore A durometer of 90 is approximately equal to a Shore D durometer of 40. The durometer of the distal tip of exemplary prior art catheters typically are in the range of 35 D to about 70 D. Such distal tips are disclosed in U.S. Pat. No. 6,652,507 issued to Pepin and U.S. Pat. No. 6,368,301 issued to Hamilton et al., the disclosures of each of which are incorporated in their entirety by reference herein.
As catheters are navigated through the vasculature, the distal tip may come into contact with a vessel wall. A hard distal tip formed of the material of the elongate shaft may injure a vessel wall such as a diseased vessel wall. There is a need to provide a catheter with a softer distal tip that can be introduced into a diseased vascular region without causing unnecessary trauma to the vasculature.